Self-adjusting telescoping concentric flue assembly

ABSTRACT

A self-adjusting, telescoping concentric flue assembly provides non-separating, substantial flexibility between the telescoping sections of both the flue and the air supply ducts. The lower flue and air supply ducts may move radially independently of each other sufficiently to permit installation even on a furnace having somewhat non-concentric flue and air inlet connections. Attachment of the lower air supply duct to the furnace insures that the lower flue is likewise attached, yet the lower air supply duct can be raised independently of the lower flue to check the connection of the latter with the furnace flue connection.

FIELD OF THE INVENTION

The present invention relates to flue assemblies of the type havingtelescoping annular air inlets as used for furnaces for mobile andmodular homes.

BACKGROUND OF THE INVENTION

The furnaces of mobile and modular homes are conventionally suppliedwith inlet air through an annular duct surrounding the furnace flue, asshown in U.S. Pat. No. 3,691,930. Failure to make or maintain agas-tight connection between the flue and the furnace may not bediscoverable by inspection, once the surrounding air supply duct issecured to the furnace.

Telescoping flue assemblies are used to accommodate variation ofdistance between furnaces and roofs. These may permit the inner flue tobe pulled down simultaneously with the attached outer air supply duct.In U.S. Pat. No. 4,522,191 seating and securing the outer duct providessome assurance that the flue connection has been made. However, withsuch assemblies, the outer duct cannot be raised independently of theinner flue to verify the flue connections. Furthermore, the type ofinterconnection shown in that patent provides limited capability fordealing with the problem presented if the furnace flue and ductconnections are not perfectly concentric.

SUMMARY OF THE INVENTION

A flue assembly embodying the present invention causes the inner flue tobe firmly seated when the outer air supply duct is pulled down andsecured to the furnace. While the duct is so attached, the flue cannotbecome separated from the furnace, as might otherwise occur, forexample, during transit. The assembly also permits the air supply ductto be raised independently of the flue, to verify that the flue remainsfirmly connected; and permit the flue to be secured to the furnace by ascrew, should this be desired. Furthermore, the assembly issubstantially self-adjusting to account for any lack of concentricitybetween flue and air duct attachment sites on the furnace.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top view of a self-adjusting telescoping concentric flueassembly embodying the present invention.

FIG. 2 is a vertical elevational view of the assembly of FIG. 1 with theright side shown in section. Phantom lines illustrate the air supplyduct in its lowermost position.

FIG. 3 is a bottom view of the assembly of FIG. 1.

FIG. 4 is a schematic of a view of the assembly about to be installed ona furnace.

DESCRIPTION OF THE PREFERRED EMBODIMENT

A self-adjusting, telescoping concentric flue assembly, generallydesignated 10, which embodies the present invention, is shown in FIG. 2.As seen from above in FIG. 1, and below in FIG. 3, the assembly 10includes a roof flashing 12 secured around the top portion of an upperair supply duct 14. The upper air supply duct 14 has, inside its topend, three brackets 16, secured to and which support the outer topportion of the upper flue 18. At the bottom end of the upper flue 18 isformed an inward extending circumferential bead 20 which limits thedownward movement of the lower flue 22 by engaging a similarly formedbead 24 which extends outward near the top of a lower flue 22, now to bedescribed.

The diameter of the lower flue 22 is sufficiently small to permitsliding of its top bead 24 within the upper flue 18, with sufficientfriction to support the lower flue 22 and permit a limited amount oftilting. At the bottom end of the lower flue 22 are secured, preferablyby spot welds, two outwardly extending angled tabs 26, positionedopposite each other.

A lower air supply duct 28, of slightly smaller diameter than the upperair supply duct 14, fits telescopingly therein beneath the brackets 16which limit its upward movement. Its telescoping fit is accompanied byenough friction to support the lower duct 28 at any height.

An abutment ring 32 is attached by brackets 34 within the lower portionof the lower air supply duct 28, spacedly above and adjacent to itsbottom edge. Both the abutment ring 32 and the stop tabs 26 extend farenough into the annular air inflow space to interfere with each other.The stop tabs 26 are always below the ring 32.

The above described flue assembly 10 can be easily installed on a mobilehome furnace, generally designated 40 and shown schematically in FIG. 4.The type of furnace 40 illustrated has a collar-like furnace flueconnection 42 and thereabout a somewhat lower air inlet connection 44,as shown.

Assuming these are preferably concentric, merely sliding the lower airsupply duct 28 down until its abutment ring 32 contacts the stop tabs 26on the lower flue 22 and continuing to move them downward together,allows the entire assembly 10 to be firmly secured to the furnace 40, byseating the lower air supply duct 28 onto the furnace air inletconnection 44. The lower flue 22 thereby will be firmly seated on thefurnace flue connection 42, as the lower air supply duct 28 comes torest around the furnace air inlet connection 44. This arrangement alsopermits inspection of the connection of the flue 22 with the furnace 40by merely raising the lower duct 28; the lower flue 22 will then remainin place as the ring 32 lifts from the tabs 26. On repositioning thelower duct 28 it may be secured to the furnace air inlet connection 44by a screw.

If the centers of the furnace connections 42, 44 are not preciselyconcentric with each other or with the upper flue 18, thecircumferential bead 24 in combination with the radial freedom of thebottom portions of both the lower flue 22 and the lower air supply duct28, nevertheless allows the assembly 10 to be easily installed. With thelower duct 28 slightly raised, the lower flue 22 is guided into positionand seated on the furnace flue connection 42, which may then be securedby a screw. The lower duct 28 is then drawn downward and out ofconcentricity with the lower flue 22 to the angular extent necessary toseat it in the furnace air inlet connection 44.

As various modifications may be made in the constructions hereindescribed and illustrated without departing from the scope of theinvention, it is intended that all matter contained in the foregoingdescription or shown in the accompanying drawings shall be interpretedas illustrative rather than limiting.

What is claimed:
 1. A self-adjusting, telescoping concentric flueassembly comprisingan upper air supply duct, an upper flue of smallerdiameter, support means at the upper portion of said upper air supplyduct securing said upper flue concentrically within said upper airsupply duct, whereby to provide an annular air inflow spacetherebetween, a lower flue fitted telescopingly within said upper flue,circumferentially formed interengaging means on the top end of saidlower flue and the bottom end of said upper flue to permit telescopingmovement therebetween without separation thereof and further to permitangular departure of said lower flue from concentricity, together with alower air supply duct fitted telescopingly within said upper air supplyduct beneath said support means, said lower air supply duct havingabutment means positioned upwardly adjacent to its bottom end andextending inward into such annular air inflow space, said lower fluehaving, adjacent to its bottom edge, stop means extending outwardly intosuch annular air inflow space below and adapted to interfere with saidinward-extending abutment means of said lower air supply duct, wherebywhen said lower air supply duct is drawn downward, such interferencecauses said lower flue to be drawn downward with it, and thereafter whensaid lower air supply duct is drawn upward said lower flue remainsdownward, thereby permitting its positioning and securement separatelyfrom the positioning and securement of the lower air supply duct.
 2. Aself-adjusting concentric flue assembly as defined in claim 1, inwhichsaid stop means attached to said lower flue comprises a pluralityof tabs outstanding therefrom, and said inward-extending abutment meansof said lower air supply duct comprises a ring spaced intermediatelybetween said lower supply air duct and said lower flue, whereby toassure such interference regardless of relative angular positioning ofsaid lower duct and flue.
 3. A self-adjusting flue assembly as definedin claim 1, whereinat any position at which said inwardly-extendingabutment means of the lower air supply duct interferes from above withsaid stop means of said lower flue, a length of said flue projectsdownwardly beyond said air supply duct, such projecting length beingsufficient along with said means to permit angular departure, to allowmanual guiding of said lower flue.